BIG PICTURE: The paperback edition of biologist Paul Ehrlich’s 1968 bestseller, The Population Bomb, was 233 pages long. The first three chapters described a problem.

The final two chapters were titled “What Needs to be Done” and “What Can You Do?” They were followed by an Appendix of examples of letters readers might send to influential individuals. In other words, 83 pages of that book (more than a third) was an unabashedly political discussion.

These pages reiterated that the future was bleak. Overpopulation threatened America, the American way of life, and the “very lives” of US citizens (pp. 135, 138, 172, 180, 182).